Hollow-fiber membranes have been widely used in water treatment, biological separation, air filtration and the like. A typical way of constructing a hollow-fiber membrane assembly involves providing a bundle of hollow-fiber membranes in a pressure bearing shell and then immobilizing the end head(s) of the bundle, or immobilizing the ends of the membrane filaments directly in the end head(s). The direct containment of a bundle of membranes in a shell and the direct immobilization of the ends of the membrane filaments in the end head(s) tend to result in knotting and fouling-up of the fiber membranes, a small throughput of the outcoming water, and a short life of the membrane assembly.
One or both ends of a hollow-fiber membrane filament are immobilized in the end head(s) of a membrane assembly in order to package the membrane filament into the membrane assembly. The joint between the hollow-fiber membrane filament and the fastening material tends to break during the operation of the membrane assembly. To avoid this problem, a practice once utilized is the filling of soft gum into the joint to prevent it from cracking. However, the soft gum tends to scale off, causing the joint between the hollow-fiber membrane filament and the fastening material cracking wholly.
Thus, the directly immobilized membrane assembly has been modified by various methods, wherein the membrane bundle is covered with a reticular protective layer according to one method, or the membranes are divided into several bundles using partition plates according to another one. Despite some protection they provide for the membranes, these methods still tend to impair the membrane bundle, break the membrane filaments, and suffer from low filtration efficiency, with the problems of water stream distribution and produced-water collection left unsolved. In particular, the problems are more serious when the diameter and the length of the membrane assembly are relatively large.
So far, a hollow-fiber membrane assembly capable of preventing the joint between the hollow-fiber membrane filament and the fastening material from cracking has not yet been available in this field.
Thus, a hollow-fiber membrane assembly capable of preventing the joint between the hollow-fiber membrane filament and the fastening material from cracking is in urgent need in this field.